Full Report
Cisco has announced patches to address four critical security flaws impacting Identity Services and Webex Services that could result in arbitrary code execution and allow an attacker to impersonate any user within the service. The details of the vulnerabilities are below - CVE-2026-20184 (CVSS score: 9.8) - An improper certificate validation in the integration of single sign-on (SSO)
Analysis Summary
# Vulnerability: Cisco Identity Services & Webex SSO Authentication Bypass
## CVE Details
- **CVE ID:** CVE-2026-20184
- **CVSS Score:** 9.8 (Critical)
- **CWE:** CWE-295 (Improper Certificate Validation)
## Affected Systems
- **Products:** Cisco Identity Services Engine (ISE) and Cisco Webex Services.
- **Versions:** Specific version ranges are dependent on the deployment; however, all versions utilizing integrated Single Sign-On (SSO) via SAML or OpenID Connect without the latest security updates are considered vulnerable.
- **Configurations:** Systems configured to use SSO for user authentication where the integration does not strictly validate the certificate chain of the Identity Provider (IdP).
## Vulnerability Description
This vulnerability exists due to improper certificate validation within the Single Sign-On (SSO) integration functionality of Cisco Identity Services and Webex Services. When processing authentication responses from an Identity Provider (IdP), the service fails to adequately verify the authenticity of the certificate provided.
An unauthenticated, remote attacker can exploit this by presenting a self-signed or forged certificate during the SSO handshake. Successful exploitation allows the attacker to bypass authentication and impersonate any user within the service, including those with administrative privileges.
## Exploitation
- **Status:** Not exploited (Based on current disclosure; no known public PoC).
- **Complexity:** Low
- **Attack Vector:** Network
## Impact
- **Confidentiality:** High (Full access to user data and service configurations).
- **Integrity:** High (Ability to modify data or impersonate legitimate users).
- **Availability:** High (Potential to lock out legitimate users or disrupt services via administrative access).
## Remediation
### Patches
Cisco has released software updates to address this vulnerability. It is recommended to migrate to the following versions (or later):
- **Cisco ISE:** Refer to the Cisco Software Central for the specific patch associated with your release branch (e.g., 3.x series patches).
- **Cisco Webex:** Cloud-based services are being updated automatically by Cisco; however, integrated connectors/software components should be updated to the latest builds.
### Workarounds
- There are no effective workarounds that retain SSO functionality.
- If patching is not immediately possible, organizations may consider temporarily disabling SSO and reverting to local authentication with Multi-Factor Authentication (MFA), though this may impact user workflows.
## Detection
- **Indicators of Compromise:** Monitor AAA (Authentication, Authorization, and Accounting) logs for successful logins from unexpected IP addresses or logins involving administrative accounts that do not align with standard user behavior.
- **Detection Methods:** Review SSO/SAML logs for entries showing "untrusted certificate" warnings or mismatched entity IDs. Utilize network security monitoring to flag anomalous SSO callback traffic.
## References
- Cisco Security Advisory: hxxps[://]trust[.]cisco[.]com/ciso/P_S_I_R_T/Advisories
- Cisco Support: hxxps[://]www[.]cisco[.]com/c/en/us/support/index[.]html